Multi-piece coil bobbin



NOV. 14, 196 7 I KORT MULTI -PIECE COIL BOBBIN Filed Dec. 15, 1965 FIG.4

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ATTORN United States Patent C) 3,352,50 MULTI-PIECE COIL BOBBIN Hans A. Kort, Lake Geneva, Wis., assignor to Sola Basic Industries, Inc., Milwaukee, Wis. Filed Dec. 15, 1965, Ser. No. 513,966 1 Claim. (Cl. 242118.4)

This invention relates to bobbins or spools for the coils or windings of inductances, transformers and the like, and more particularly to a multi-piece bobbin that can be stored in a fiat or knocked-down condition and readily assembled into spool form.

In prior bobbins of this character, it has been necessary to provide the assembled spool with a separate strip of relatively stiff insulating material to retain the bobbin in assembled condition, such as in US. Patent No. 1,895,776 to Stolp, or the side members of the core portion are provided with tongue and slot connections which provide undesirable flange-like projections or ribs on the core portion as in US. Patent No. 3,108,763 to Ahlene.

An object of the present invention is to provide a new and improved structure for a bobbin of the multi-piece knock-down type.

A further object of the invention is to provide a new and improved multi-piece bobbin which can be quickly and readily assembled from flat sheets and which is rigid- 1y retained in the assembled spool form.

A still further object of the invention is to provide a bobbin of this character which is rigidly retained in assembled form without the use of extraneous materials and which provides a smooth outer core or coil Winding surface free from projecting ribs or the like.

In a preferred aspect, the invention comprises three pairs of members made from flat sheet material, one of said pairs forming the end pieces of the assembled spool, and the other two pairs forming the sides of the core or coil winding portion. Each of the end pieces has similar rectangular apertures or openings adapted to receive opposite ends of the side members, each end piece being further provided with a pair of integral tabs extending inwardly from two opposite sides of the opening. One pair of the side members has notches adapted to interlock with the tabs on the end pieces, and also has integral tabs adapted to interlock with notches provided in the other pair of side members. Both ends of the lastmentioned pair of side members include laterally extending integral tabs adapted to bear against the outer faces of the end pieces, the entire arrangement of tabs and notches being such that when the parts are assembled and snapped into position, a self-contained rigid bobbin or spool having a smooth core or coil winding surface is provided. If desired, one or both of the end pieces may be provided with notches and/ or openings for receiving wire ends and terminal connectors.

The above and other objects, features and advantages of the invention will become apparent from the following description and accompanying drawing which are merely exemplary.

In the drawing:

FIG. 1 is a perspective view of the assembled bobbin;

FIG. 2 is a plan view of one of the pairs of end pieces;

FIG. 3 is a plan view of one of the pairs of side members; and

FIG. 4 is a plan view of the other of the pairs of side members.

Referring to the drawing, and particularly to FIG. 1, the bobbin is shown as comprising a pair of end pieces 14, upper and lower side pieces or members 16, and a second pair of side pieces or members 18. The pair of end pieces or members 14, the pair of upper and lower side members 16, and the other pair of side members 18 are each of the same size and shape, and thus only one member of each pair is illustrated in FIGS. 2-4 of the drawing. Each of the members comprises a flat sheet of insulating material having a thickness sulficient to give the desired rigidity to the assembled device and also having sufficient flexibility and resiliency to permit snapping the last piece into the assembled structure. Such material, for example, may comprise a glass-reinforced polyester such as Insulstruc, the main requirement being that it be strong and relatively rigid as well as semiflexible.

As shown in FIGS. 1 and 2, the end pieces 14 may include a centrally disposed opening or cut-out portion 20 within which the ends 22 and 24 of the side members 16 and 18 are adapted closely to fit. The size of the opening 20 and the corresponding widths of the side members 16 and 18 can be varied to provide a core portion 26 of any desired size and cross sectional area. The end pieces 14 are also provided with a pair of integral tabs 28 which extend outwardly into opening 20 from two opposite sides 30 of the opening.

As shown in FIGS. 1 and 3, the upper and lower side members 16 are of generally rectangular shape, and at each end 22 thereof there is a pair of laterally or outwardly extending integral tabs 32 which are positioned outwardly of the end pieces 14 in the assembled structure. Tabs 32 are adapted to bear against the outer faces or surfaces of the end members as shown in FIG. 1. Each of the upper and lower side members 16 is also provided with a pair of notches 34 which extend inwardly from the sides 36 to which the tabs 32 are attached. The width of the members 16, i.e., the distance between the sides 36, is substantially the same as the width of the opening 20 in the end pieces 14, so that the upper and lower side members 16 fit rather closely between the edges or sides 30 of the opening 20 when the bobbin is assembled and the tabs 32 extend outwardly from continuous or uninterrupted portions of the sides 36.

As shown in FIGS. 1 and 4, the remaining pair of side members 18 is of generally rectangular shape and is provided with a pair of notches 38 which extend inwardly from the end edges 24 and a pair of integral tabs 40 which extend laterally outward from the sides 42 of the member. The notches 38 are of such size as to interlock with the tabs 28 of the end pieces 14, and the tabs 40 are of such size as to interlock with the notches 34 of the upper and lower side members 16 as shown in FIG. 1. The width of side members 18 between the side edges 42 is such that the members 18 fit closely between the upper and lower side member 16 when the bobbin is assembled, the height of the opening 20 in end pieces 14 being equal to the width of member 18 plus the thickness of the upper and lower members 16. The length of the side members 16 is preferably such that the ends 24 are flush with the outer faces of the end pieces 14 when assembled.

From the foregoing description, it will be evident that when the bobbin is disassembled or knocked-down, all of the parts can be stacked flat and occupy very little space for shipping and storage. In order to assemble the bobbin, the upper and lower side members 16 are tilted about their longitudinal axes and slipped through the openings 20 in end pieces 14, so that the tabs 32 are positioned outwardly of the end pieces. One of the side members 18 is next inserted to space the upper and lower members 16 and to press their upper and lower sides respectively against the upper and lower edges or sides of the openings 20. At the same time, notches 38 of the side member interengage a tab 28 on each of the end pieces 14, and the tabs 40 of the side member 18 interengage and interlock with the notches .34 of upper and lower members 16. The remaining side member 18 is then inserted and snapped into position with its notches and tabs interlocking with tabs and .notches on the end pieces and the upper and lower members in the same manner as the opposite side 18. The end pieces 14 are thus pressed vor clamped against the tabs .32 and are retained in proper spaced relationship by engagement of the inner sides or walls of notches 38 with tabs 28 without the need of slots or the like in members 16 adjacent the tabs 32. The side members 18 are maintained in proper spaced relationship by tabs 40 and notches 34. The upper and lowerside wall members 16 are maintained 'in proper .spaced relationship by the interposed side wall members Thus, the resultant bobbin or spool of the multi-piece or knock-down type is simple in construction, easy to .assemble, and very rigid in assembled form. Furthermore, a smooth core or coil winding portion free of projecting ribs or the like .is provided without the use of any extraneous material. One or both of the end pieces 14 may be provided with notches 50 and/or apertures 52, for example, for receiving leads to the coil winding and terminal connectors.

Other features, changes and modifications may also be incorporated in the described and illustrated embodiment of the invention without departing from the spirit of the invention, and it is intended that the invention be limited only by the scope of the appended claim.

What is claimed is:

A multi-piece bobbin of the knock-down type for Wire coils comprising a pair of end pieces, each having .:a substantially central opening with tabs projecting inwardly into the opening from opposite sides thereof; a pair of side members for the core portion of said bobbin, each having a pair of lateral tabs at both ends thereof extending directly outward from a continuous surface of said side members for engaging the outer faces of said end pieces; and a second pair of side members for said core portion adapted to fit between said first-mentioned side members and provided with notches in the "end portions thereof adapted to interengage with said tabs on the end pieces to clamp and retain the end pieces in predetermined spaced relation on said core portion with said second pair of side members confined within said openings of said end pieces; each of said first-mentioned side members being further provided with a notch intermediate said laterally extending tabs, and each-of said .second pair of side members being further provided with an outwardly extending tab adapted to interengage with said lastmentioned notches to retain the second pair of side members in spaced relationship.

References Cited UNITED STATES PATENTS 1,895,776 1/ 1933 Stolp 242-1 187 X 1,997,641 4/1935 Isenberg 242-1187 2,229,413 1/ 1941 Joost '242--118.8 2,428,826 -1-0/ 1947 Bauer 2'42--118;4 X 3,108,763 10/ 1963 Ahlene 2'42-1 15 FOREIGN PATENTS 646,957 11/1950 Great Britain. 651,658 4/ 1951 Great Britain.

GEORGE F. MAUTZ, Primary Examiner. 

